But the Federation of Small Businesses (FSB) said that winning government work was already too complicated.

“The FSB is behind the skills pledge because we need better skilled employees, but there are already plenty of hoops small businesses have to jump through to get government work, so we would be concerned if it became compulsory,” a spokesman said.

“All central government departments have signed the skills pledge, but that is not enough,” he said. “Private companies with good training records look beyond their own workforce and understand that their suppliers are as important to their success as their own staff.

“The public sector employs one-quarter of this country’s workforce. Add those who supply the public sector and we are talking about a real opportunity to build the skills base.”